This invention relates to detecting leakage in underground tanks and conduits using neutron back scatter gauge in combination with gas analysis.
Neutron gauge utilizes a source of fast neutrons and a detector for slow neutrons. Presence of hydrogen-bearing material, such as organic liquid is detected by change in the number of slow neutrons counted in the detector. The number of backscattered slow neutrons is directly related to the number of hydrogen atoms present for slowing the fast neutrons from the source.
In the prior art, neutron detectors have been used in well logging. Examples of these applications are seen in Mills, Jr., U.S. Pat. No. 4,268,749.
There is a need for detecting leaks in underground tanks, particularly tanks that were installed decades ago, using non-destructive and non-invasive method that is at the same time economical and efficient. There is also a need to determine the rate of leak.